This invention relates to drill rigs and to the handling of equipment at drilling sites.
The scale of operations for drilling gas and oil wells requires considerable resources of equipment and time. The present invention is concerned with the provision of apparatus that can promote the efficient use of well drilling plant.
One of the factors limiting efficiency lies in the capabilities of mechanical handling systems that are able to deal effectively with the cumbersome components with which a well is drilled and lined.
In particular, the elongate tubular elements for drilling a well and for lining the well are normally transported and stored in a horizontal position for a number of practical reasons and must then be brought upright to be positioned coaxially with the drill string when they are brought to use.
It is known (U.S. Pat. Nos. 4,403,879, 4,303,270, 4,403,666 and 4,407,629) to provide a pipe boom that swings tubular elements from a horizontal position to a vertical position. While the boom is horizontal, the pipes are placed or are run into gripping jaws of the boom. With the jaws holding and supporting the pipe, the boom is pivoted to an upright position which brings the pipe to the drilling axis. Such handling equipment has only a limited use, however. In most cases it is still necessary to provide handling means that will lift the individual pipe elements and place them in the jaws of the horizontal boom. In U.S. Pat. No. 4,407,629, although it is arranged that each tubular element rolls into the jaws, when a drill string is subsequently being dismantled it is still necessary to have further handling means to lift the individual elements to remove them from the jaws.
The manipulation and utilization of drill rig equipment are also factors in the efficiency of operation of drill rigs. The need for heavy lifting gear, for example, is a considerable drain on resources and such equipment may be kept on site over the period of drilling operations, for example when it is required to drill a number of holes at the same site. Because of the difficulties from disturbing and resetting an installation, once the equipment is on site it may remain until all its work has been completed, even though there may be long periods of waiting time during which the equipment is idle.
One object of the present invention is to provide an improved means for handling tubular well drilling elements when they are to be transferred between a storage location and the drilling axis.
Another object of the invention is to provide an arrangement which facilitates the manipulation of drill rig equipment.